1. Field of the Invention
The present invention relates to the field of computer-aided design for sheet metal parts. More particularly, the present invention relates to guaranteeing sketches for every flange of a 3D sheet metal part, no matter how the part was generated.
2. Background Information
Sheet metal part designers typically think of flanges as 2D problems. When designing a new 3D sheet metal shape on a computer-aided design (CAD) system, it is therefore often more convenient and simpler for sheet metal designers and manufacturers to operate with 2D representations at the flange level. Current 3D CAD systems, however do not guarantee 2D sketches for every 3D sheet metal part. Thus, the sheet metal manufacturing industry is not widely using 3D CAD systems for sheet metal part design.
One easy way to create a basic 3D sheet metal part shape (which can be modified later) is to use a sheet metal feature operation, such as a profile extrusion, as seen in FIG. 1A. Unfortunately, current 3D sheet metal CAD systems do not generate 2D sketches for parts created by all sheet metal feature operations. For example, current systems represent a shape created by a profile extrusion operation with a single profile sketch and its material property. That is, 2D sketches for each created flange are not generated. Consequently, it is difficult for the designer to alter the shape of the flanges of the 3D part.
Currently, an editing operation of even a simple flange requires a patchwork process involving 2D and 3D manipulations, an example of which is shown in FIG. 1B. More specifically, after creating a flange 1, the user enters a sketch mode (which shows the flange 1 being edited in 2D) and then creates a 2D shape 2 that will be added to or deleted from the original flange 1. In this example, the shape will be added. The user must then convert the 2D shape 2 into a solid shape 3, and then blend the solid shape 3 with the original flange 1 to create the modified flange 4.
Not only is the editing process overly complicated, but the display showing a previously edited part is unnecessarily cluttered. Typically, the user is not interested in seeing how the part was created. As seen in FIG. 1C, however, a flange 5 that had been edited by adding the new portions 6, 7, 8 shows the history of shapes that were used to created the edited flange. Thus, the user is required to view the patchwork process used to create the edited part when making further edits. In other words, in systems of the prior art the screen becomes unnecessarily cluttered.
It would be desirable to have a software application that permits easy editing of a 3D part created by any type of sheet metal feature operation. Such a system should create sketches for each flange of the 3D part to permit easy editing of the flange in 2D.